how to keep Smooth mode from making ripples?
You need to add an edge split modifier to make the mesh look right.
Method 1 - modifier

Select Mesh

Add Edge Split modifier


Method 2 - specify shading
Another method you can use it a bit more manual and not a one click solution but it will work just as well in this case.

Select the mesh and go into edit mode.

Select the top polygons that make up the flat surface

Set their shading to flat in the tool panel on the left (t)